Some day soon, when pro-democracy campaigners have their cellphones confiscated by police, they'll be able to hit the "panic button" -- a special app that will both wipe out the phone's address book and emit emergency alerts to other activists.

The panic button is one of the new technologies the U.S. State Department is promoting to equip pro-democracy activists in countries ranging from the Middle East to China with the tools to fight back against repressive governments.

"We've been trying to keep below the radar on this, because a lot of the people we are working with are operating in very sensitive environments," said Michael Posner, assistant U.S. secretary of state for human rights and labor.

The U.S. technology initiative is part of Secretary of State Hillary Clinton's push to expand Internet freedoms, pointing out the crucial role that on-line resources such as Twitter and Facebook have had in fueling pro-democracy movements in Iran, Egypt, Tunisia and elsewhere.